Synonyms for adult Found 7 synonyms across 3 meanings for “adult”. a fully developed person from maturity onward (noun) grownup (of animals) fully developed (adj) bigfull-growngrowngrownup designed to arouse lust (adj) pornographic Explore Related Words Rhymes with adultSynonyms for grownupSynonyms for bigSynonyms for full-grownSynonyms for grownSynonyms for grownup Synonym Finder | Rhyme Finder | Poetry Editor